Automatic reclosing circuit breaker system



Aug. 13, 1935.

SYSTEM Inventor:

Richard A. Hammond.

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. which are well known in the a Patented Aug. 13, 1935 PATENT OFFICE AUTOMATIC RECLOSING IRCUIT BREAKER SYSTEM Richard A. Hammond, Kansas City, Mo., alsignor to General Electric Company, a corporation of New York Application March 31, 1934, Serial No. 718,428

7 Claims.

My invention relates to automatic reclosing circuit breaker systems and particularly to such systems in which a circuit breaker is arranged to be opened in response to a predetermined abnormal condition on the circuit controlled by the circuit breaker and particularly to such systems in which the circuit breaker is arranged to be reclosed a predetermined number of times with predetermined time intervals between successive reclosures, if the abnormal condition causing the opening of the circuit breaker is of a permanent character.

An object of my invention is to provide an arrangement whereby in such an automatic reclosing circuit breaker system the control of the opening of the circuit breaker by the abnormal circuit condition is varied in accordance with the number of times the circuit breaker has been opened and reclosed. For example, in some cases it is desirable to have the first opening of the circuit breaker effected immediately upon the occurrence of a predetermined abnormal condition and after the first reclosure of the circuit breaker to have any subsequent opening of the circuit breaker effected in response to said predetermined abnormal condition only after the circuit breaker has remained closed for a predetermined time.

My invention will be better understood from the following description, when taken in connection with 'the accompanying drawing the single figure of which diagrammatically illustrates an automatic reclosing circuit breaker system embodying my invention, in which the first reclosure occurs immediately after the first opening thereof and the subaquent reclosures occur only after the circuit breaker has remained open for a relatively longer period of-time, and the scope of my invention will be pointed out in the appended claims.

Referring to the drawing, I represents a suitable circuit breaker, examples of which are well known in the art, for connecting a grounded supply circuit 2, which may be supplied from any suitable source, to a load circuit 3. As shown in the drawing, the circuit breaker I is of the well-known latched-in type and comprises a closing coil 4, which, when energized. closes the circuit breaker I, a latch I for holding the circuit breaker in its closed position and a trip coil 8 which, when energized, releases the latch and allows the circuit breaker to open.

Suitable fault responsive means, examples of are provided for eilecting the opening of the circuit breaker I. As shown in the drawing, the fault responsive means includes three over-current relays 1, 8 and 9 which are respectively connected in series relation with different phases of the supply circuit 2, and an instantaneous ground fault 5 relay 50 and a time delay ground fault relay 5| which are connected in any suitable manner, examples of which are well known in the art, so that they are operated by a ground on any phase conductor of circuit 3 when circuit breaker I 10 is closed. The relays I, 8 and 9 are provided with instantaneous contacts III, II and I2, respectively, and time delay contacts I 0', II and I2 respectively. Each of these relay contacts is connected in series with the trip coil 6 and the auxiliary contacts I3 on the circuit breaker I so that an'energizing circuit for the trip coil 6 is completed to effect the opening of the circuit breaker when the current in any phase of the supply circuit 2 exceeds a predetermined value. While I have shown each of the relays I, II and 9 as having both instantaneous and time delay contacts in order to simplify the disclosure, it is obvious that in practice a separate over-current relay may be provided, if desired, 26 to control each of these contacts.

The relays 50 and ii are provided with contacts 52 and 53, respectively, which are connected in series with each other and in series with the trip coil 6 so as to effect the opening of the 30 circuit breaker I when a ground fault occurs on the circuit 3.

For eil'ecting a single instantaneous reclosure of the circuit breaker I after the initial opening thereof in response to an abnormal load condition on the load circuit, a control device I5 is provided which, as shown in the drawing, comprises two electromagnets I6 and I1 and a latch II being arranged to be tripped by the magnet it when it is energized. Under normal operating 40 conditions the magnet I1 is held in its energized position by the latch I8 and in that position the contacts I9, 54 and 55 are closed and the contacts 2| and 2I are open. Also under normal operating conditions the magnet I6 is deenergized so'that 5 its contacts 22 and 23 are open,

The winding 24 of the magnet I 6 is connected in series with the normally closed contacts I9 and the auxiliary contacts 25 on the circuit breaker I when it is open so that, as soon as the circuit breaker I opens, the magnet I Ii is energized to close its contacts 22 and 23 and also to trip the latch I8 so that the contacts I9, 54 and 55 are opened and the contacts 2! and 2i are closed.

The closing of the contacts 23 completes a lock- 55 ing circuit for the winding 23 of the magnet i5 so that it remains energized, after the opening of the contacts i9, until the circuit breaker l closes and opens its auxiliary contacts 25. The closing of the contacts 22 and 23, which are connected in series, completes an energizing circuit for a control relay 29 which, in turn, completes an energizing circuit for the closing coil 4 of the circuit breaker i. As soon as the circuit breaker i closes, the magnet 16 becomes deenergized and opens its contacts 22 and 23. Since the contacts l9 are now open, the original energizing circuit for the winding E i cf the magnet I6 is open and, therefore, the magnet it cannot be energized again until the winding 21 of the magnet I1 is energized to eflect the closing of the contacts I9. Consequently, if the circuit breaker I should open immediately after its first reclosure, the circuit breaker is prevented from being reclosed thereafter for a predetermined time. Suitable means are provided, as will be hereinafter described, for effecting the energization of the winding 21 of the magnet I! if the circuit breaker l is still closed at the expiration of a predetermined time interval after a reclosure thereof.

In order to effect the reclosing of the circuit breaker I a predetermined number of times with relatively long predetermined time intervals be tween successive reclosures in case the circuit breaker does not remain closed after the initial instantaneous reclosure, and in order to limit the number of such time delayed reclosures, a suitable-motor-operated reclosing device 21, exam-- ples of which are well vided. As shown in the device comprises a timer 28 and a substantially constant speed driving motor 29 therefor, which is permanently connected to a suitable source of current such as the supply circuit 2. The motor 28 is normally prevented from rotating by a stop 30 which engages a projection 3| on the timer 28. The stop 38 is arranged to be moved out of engagement with the projection 3| by a release magnet 32 when it is energized. The winding of the magnet 32 is connected in series with the contacts 2| of magnet l1 and contacts 33 of the control relay 26 so that when relay 26 is energized, to eifect the initial reclosure of the circuit breaker I, it also effects the energization of the release magnet 32 to start the reclosing device 21 into operation. In certain cases contacts 33 may be omitted from this circuit.

The timer 28 is provided with two sets of contacts 34 and 35 which are arranged to be closed successively, as the timer rotates, with predetermined time intervals between successive closures thereof. The'contacts 34 and 35 are also arranged so that only one set can be closed at any instant. When the contacts 34 are closed, a circuit is completed for a control relay 36 associated with the timer 28 if at the same time the circuit breaker l is open so that its auxiliary contacts 25 are closed. The relay 35, when energized, completes a locking circuit for itself so that the relay remains energized when the contacts 34 are subsequently opened. When the contacts 35 are closed and the relay 36 is also energized at the same time, a circuit is completed for the control relay 26 to establish an energizing circuit for the closing coil 4 of the circuit breaker I.

After the timer 28 has been in operation for a predetermined time and the contacts 34 and 35 have been closed a predetermined number of times, the timer is arranged to interrupt the connection between contacts 39 and 40 and to circuit breaker known in the art is prodrawing, this reclosing.

protective devices I, 8

establish a connection between contacts 39 and ii. If the circuit breaker i is closed at the time the contacts 39 and M are connected together, a circuit is completed for the winding 21 of the magnet ll so as to restore it to its energized or normal position in which position it is held by the latch iii. If, however, the circuit breaker is open at the time the contacts 39 and M are connected together, the magnet ll remains deenergized and no further automatic reclosing ofthe circuit breaker can take place until after a suitable manual operation, such as the movement of the magnet I! to its energized position, has been performed.

In order that circuit breaker i may initially open instantly upon the occurrence of a ground fault and only after a predetermined time interval if the ground fault still exists after the first reclosure, I connect the normally closed contacts 54 of the magnet I! in parallel with the contacts 53 of the time delay ground relay 5|. Therefore, if the ground fault still exists after the first reclosure, the next opening of the circuit breaker l is not effected until sufficient time has elapsed to allow relay 5! which is calibrated to respond substantially to the same value of ground current as relay 59 to close its contacts 53.

Also, in order that the circuit breaker I may be initially opened instantly upon the occurrence of a predetermined abnormal value of current in any phase conductor of the circuit 3 when the l is closed and only after a predetermined time interval if the abnormal circuit condition still exists after the first reclosure,

I connect the normally closed contacts 55 of the magnet 11 in series with the parallel-connected instantaneous contacts 10, H and I2 of the overcurrent relays I, 8 and 9 respectively. Therefore, after the initial reclosure of the circuit breaker I, the instantaneous contacts III, II and I2 of the and 9 respectively cannot again effect the immediate opening of the circuit breaker l until the magnet I1 is resorted to its normal position.

The operation of the arrangement shown in the drawing is as follows: When the circuit breaker l is closed, it is held in its closed position by the latch 5 as long as conditions on the load circuit are normal. When an abnormal condition, such as a ground fault, occurs which causes one or more of the protective relays, such as the ground relay 50, to close its contacts instantly, a circuit is then immediately completed, through the auxiliary contacts l3 on the circuit breaker and the contacts of the operated relay, for the trip coil 6 to effect the immediate opening of the circuit breaker I. As soon as the circuit breaker l opens, its auxiliary contacts 25 complete, through the contacts 19 of the magnet l1 and the contacts 39 and 40 of the timer 28, an energizing circuit for the winding 24 of the magnet I8. By closing its contacts 23, the magnet 24 completes, independently of the contacts l9, a locking circuit for its winding so that the magnet I6 is not deenergized by the subsequent opening of the latter contacts. The energization of the magnet l6 also trips the latch l8 so that the magnet ll moves to its deenergized position and in so doing opens its contacts [9, 54 and 55 and closes its contacts 28 and 2|. As soon as the contacts 28 are closed, an energizing circuit is completed for the control relay 25 through the contacts 22 of the energized magnet I6 and the contacts 39 and 40 of the timer 28. By closing its contacts 43, the control relay 26 completes a circuit for the closing coil 4 to close the circuit breaker I. By closing its contacts 33 the control relay 26 also completes, through the contacts 2| of the magnet I'I, an energizing circuit for the release magnet 32 of the reclosing device 21'.

When the circuit breaker I closes, the circuit of the winding 24 is interrupted at the auxiliary contacts 25 so thatthe magnet I6 becomes deenergized and opens its contacts 22 and 23. Since the magnet I1 is now in its deenergized position, the contacts I9 thereof are open so that, if the circuit breaker I should open after its first reclosure, the magnet I6 is prevented from effecting another instantaneous reclosure.,

Also since the contacts 54 of the magnet I! are now open, it is evident that if the abnormal condition, which it was assumed was a ground fault, is still connected to the circuit 3 after the inl stantaneous reclosure of the circuit breaker I,

this ground fault will not effect the subsequent opening of the circuit breaker I until after the circuit breaker has remained closed for a suflicient length of time to allow the time delay ground fault relay 5| to close its contacts 53 in parallel with the open contacts 54.

As soon as release magnet 32 of the reclosing device 21' is energized in response to the initial opening of the circuit breaker I, the timer 28 starts to rotate and after it has been in operation for a predetermined length of time, it closes the contacts 34. If at that time the circuit breaker I is open, a circuit is completed through the auxiliary contacts 25 on the circuit breaker I, the winding of relay 36, contacts 34 and the contacts 39 and 40 of the timer 28 to effect the energization of the relay 36, Relay 36 by closing its contacts 44 completes, independently of the contacts 34, a locking circuit for its operating winding so that the relay remains energized after the timer 28 opens its contacts 34.

When the timer 28 subsequently closes its contacts 35, a circuit is completed for the control relay 26. This circuit includes contacts 45 of the relay 36 and contacts 35, 44, 4 0 and 39 of the timber 28. The control relay 26 then effects, in the manner above described, the energization of the closing coil 4 so as to close the circuit breaker I. The control relay 26 also effects the energization of the release magnet 32 which, however, has no effect at this time because the timer 28 is not in its normal position.

If following this reclosure the circuit breaker I should open again, the timer 28, in the manner above described, effects another reclosure of the circuit breaker a predetermined time after the previous reclosure.

After the timer 29 has successively closed and opened its contacts 34 and 35 a predetermined number of times, it disconnects contact 39 from contact 49 and then connects contact 39 to contact 4|. If the circuit breaker I is closed at this time, a circuit is completed through the contacts 39 and 4| and the auxiliary contacts 46 on the circuit breaker I for the winding 21 of the magnet II. fIhe magnet I I is then restored to its normal position in which position it is held by the latch I8. The instantaneous ground relay 50 is now operative again to effect the immediate opening-of the circuit breaker I.

The contacts 39 and 40 are disconnected from each other at this time by the timer 28 in order, to prevent pumpingof the circuit breaker I in case a permanent fault should occur while the contacts 39 and 4| are connected together. It is obvious that if a permanent fault should occur while the contacts 39, 40 and 4| are all connected together, the circuit breaker I would be instantaneously reclosed in a manner above described after each opening thereof and would be opened immediately after each reclosure. By having the contacts 40 disconnected from the contact 39, such pumping of the circuit breaker cannot occur because the circuit of the magnet I6 is opened while the closing circuit for the magnet I1 is completed.

After the contacts 39 and 4| have been connected together for a sufficient length of time to effect the restoration of the magnet I! to its normal position, the timer 28 disconnects the contact 39 from the contact 4| and again connects the contact 39 to the contact 40. The timer 28 then returns to its normal position where it is stopped by the projection 3| engaging the stop 30.

If the abnormal condition which causes the circuit breaker to open is an abnormal current which operates one of the over-current relays, such for example as the relay I, the initial closing of the instantaneous contacts of this over-current relay completes through normally closed contacts of magnet I! a circuit for the trip coil 6 to effect the immediate opening of the circuit breaker I. After the first reclosure of the circuit breaker any subsequent operation of an overcurrent relay while the magnet I'I remains in its deenergized position does not effect the opening of the circuit breaker until suflicient time has elapsed for the over-current relay to close its time delay contacts.

While I have, in accordance with the patent statutes, shown and described my invention as applied to a particular system and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:-

1. In combination, an electric circuit, a circuit breaker in said circuit, means responsive to a predetermined abnormal condition of said circuit for controlling the opening of said circuit breaker, means responsive to the opening of said circuit breaker for effecting the reclosure thereof, and means for causing said abnormal circuit condition responsive means to control the opening of said circuit breaker in one predetermined manner prior to a predetermined opening of said circuit breaker and in a different predetermined manner after said predetermined opening of said circuit breaker.

2. In combination, an electric circuit, a circuit breaker in said circuit, means responsive to a predetermined abnormal condition of said circuit for controlling the opening of said circuit breaker, means responsive to the opening of said circuit breaker for eifecting the reclosure thereof, and means for causing said abnormal circuit condition responsive means to control the opening of said circuit breaker in one predetermined marmer prior to the initial opening thereof and in a different predetermined manner after the initial reclosure thereof.

3. In combination, an electric circuit, a circuit breaker in said circuit, means responsive to a predetermined abnormal condition of said circuit for controlling the opening of said circuit breaker, means responsive to the opening of said circuit breaker for effecting the reclosure thereof, and

means for causing said abnormal circuit condition responsive means to effect the immediate opening of said circuit breaker prior to the initial opening thereof and to effect the opening thereof after a predetermined time interval subsequent to the initial reclosure thereof.

4. In combination, an electric circuit, a circuit breaker in said circuit, means responsive to a predetermined abnormal condition of said circuit for effecting the opening of said circuit breaker at two different time intervals after an occurrence of said abnormal condition, means responsive to the opening of said circuit breaker for effecting the reclosure thereof, and means responsive to a predetermined opening of said circuit breaker for rendering said abnormal condition responsive means inoperative to effect a subsequent opening of said circuit breaker at one of said time intervals after the occurrence of said abnormal condition.

5. In combination, an electric circuit, a circuit breaker in said circuit, means responsive to a predetermined abnormal condition of said circuit for effecting the opening of said circuit breaker at two different time intervals after an occurrence of said abnormal condition, means responsive to the opening of said circuit breaker for effecting the reclosure thereof, and means responsive to the initial opening of said circuit breaker for rendering said abnormal condition response means inoperative to effect a subsequent opening of said circuit breaker at the shorter of said time intervals.

6. In combination, an electric circuit, a circuit breaker in said circuit, means responsive to a predetermined abnormal condition of said circuit for effecting the immediate opening of said circuit breaker and the opening of said circuit breaker after a predetermined time interval upon the occurrence of said predetermined abnormal condition, means responsive to the opening of said circuit breaker for effecting after a time interval the reclosure thereof, a relay for rendering said opening means inoperative to effect an immediate opening of said circuit breaker and means responsive to the initial opening of said circuit breaker for effecting the operation of said relay.

7. In combination, an electric circuit, a circuit breaker in said circuit, means responsive to a predetermined abnormal condition of said circuit for effecting the immediate opening of said circuit breaker and the opening of said circuit breaker after a predetermined time interval upon the occurrence of said predetermined abnormal condition, means responsive to the opening of said circuit breaker for effecting after a time interval the reclosure thereof, a relay for rendering said opening means inoperative to effect'an immediate opening of said circuit breaker and means responsive to the initial opening of said circuit breaker for effecting the operation of said relay for a predetermined time so that during said predetermined time the opening of said circuit breaker is controlled by said time delay opening means.

RICHARD A. HAMMOND. 

